| 摘要 |
<p>An apparatus for recording and reproducing optical information in which, on an optical information carrier provided beforehand with guide grooves for tracking and information pits, a main light beam for recording and reproducing information and a pair of sub-light beams for sensing tracking are projected, and further, on the optical information carrier, the scanning traces of the centers of the sub-light beams are located on both the sides of the scanning trace of the center of the main light beam. Provided are a first and a second means which generate electrical signals respectively corresponding to the intensities of the sub-light beams reflected by the optical information carrier, a third means which senses the difference between the amplitudes of the electrical output signals of the first and second means, a fourth means which senses the AC components of the electrical output signals of the first and second means and senses the difference between the amplitudes of the AC components, and a fifth means which selects the output sensed by the third means as tracking information when the sub-light beams scan the region where no information pit is provided and selects the output sensed by the fourth means as tracking information when the sub-light beams scan the region where the information pits are provided.</p> |
